Plastic injection-moulded part with embedded component

ABSTRACT

A method for producing a plastic injection-molded part having an insert made of a material different from the plastic material is provided, the method comprising the steps of: (a) introducing and positioning the insert in a cavity of an injection mold; (b) setting the clamping force of the injection mold on a clamping mechanism to a maximum force predetermined by the material of the insert; and (c) seamlessly encapsulating the insert with the plastic material of the plastic injection-molded part inside the injection mold, wherein the encapsulating is seamless or complete.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of U.S. patent application Ser. No.11/014,370, filed on Dec. 16, 2004 (now U.S. Pat. No. 7,943,090, whichclaims priority under 35 U.S.C. §119, via the Paris Convention for theProtection of Industrial Property, to German patent application numberDE 103 59 303.9, filed Dec. 17, 2003, all which are hereby incorporatedby reference.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

The invention relates to a method for production of a plasticinjection-moulded part having a component made of ceramic or glassembedded in it, which plastic injection-moulded part can be a shell bodyof a rapid diagnosis appliance.

(2) Description of Related Art

In rapid diagnosis appliances, such as those used for determining bloodsugar levels or for determining other blood values, it is oftennecessary to heat the reagent area inside the appliance housing of therapid diagnosis appliance. Test strips wetted with human or animalblood, for example, are inserted into the evaluation area of a rapiddiagnosis appliance. It is also possible to first introduce the teststrip into the rapid diagnosis appliance and only thereafter apply thesample to the test strip. The test strips contain substances which reactwith the area of the test strip wetted with the blood of human or animalorigin. To perform a measurement procedure yielding a meaningfulmeasurement result, a defined temperature is needed during theevaluation procedure.

To generate an appropriate temperature level, metal or ceramic heatingelements are therefore integrated in the interior of the housing body ofthe rapid diagnosis appliance. These heating elements are normallyembedded in plastic components in the critical system environment. Theheating elements made of metal or ceramic materials are generallyembedded by mechanical securing with springs or clip elements, or byadhesively bonding the heating element made of metal or ceramic into adepression provided for this purpose in the plastic material.

The disadvantages of mechanically securing the ceramic or metal heatingelement inside a plastic component are that the spring elements or clipelements exerting spring forces on the heating element can inducestresses in a heating element made of ceramic for example, which canlead to its fracturing, with the result that the heating elementintegrated for example in the rapid diagnosis appliance is renderedunusable. Moreover, when the heating element is mounted mechanically inthe inside of the housing, the resulting seams, caused by productiontolerances, may mean that if too much blood is applied to the teststrip, blood can pass through the seams into the inside of the applianceand cause damage there to the evaluation electronics. The same appliesto a cleaning agent with which the inside of the appliance is cleanedafter several test strip evaluations in order to remove dried bloodplasma which, for example, has accumulated on the heating element madeof metal or ceramic. The cleaning agents used are often very aggressiveso as to be able to dissolve and remove the blood plasma which hasaccumulated mainly on the surface of the metal or ceramic heatingelement. If the cleaning agent, which often has an extreme dissolvingaction, passes into the inside of the appliance through the seams whicharise in mechanical mounting of the metal or ceramic heating element,then the electronics may also be damaged by the cleaning agent.

The option of mechanically securing a ceramic or metal heating elementinside a rapid diagnosis appliance additionally has the disadvantage ofhigh costs of assembly, and the risk of incorrect assembly is notinconsiderable. If a heating element to be introduced at a later stageinto a plastic component is incorrectly assembled, this can result intemperature control errors which may have the effect that themeasurement results obtained from an evaluation of a test strip insertedinto the rapid diagnosis appliance are often rendered unusable.

Instead of the mechanical securing option, the heating element made ofmetal or ceramic material can also be adhesively bonded into acorresponding depression of a half shell in the inside of the rapiddiagnosis appliance. By adhesively bonding a metal or ceramic heatingelement into a recess in the inside of the rapid diagnosis appliance, itis possible to largely avoid the seams which arise in the securingoption discussed above, but the solvents admixed to the adhesive canaffect the test strip inserted into the inside of the appliance.Moreover, it is not possible to avoid a situation where the cleaningagents, with which the heating element is cleaned in order to removedried blood plasma from time to time, dissolve the adhesive with whichthe heating element is bonded into a depression inside the housinginterior. Moreover, all adhesives are subject to aging during the periodof operation, particularly in the event of large temperaturefluctuations, which means that this securing option is associated withrisks concerning the reliability of a rapid diagnosis appliance over theperiod of its use.

Moreover, in this type of securing, the high cost of assembly is adisadvantage if this option is used in large-scale production, forexample as in the large-scale production of rapid diagnosis appliances.Here too, the production process is not free from assembly errors which,in accordance with what has been stated above, can considerablycompromise the meaningfulness of the evaluation result obtained.

A further option for securing a component, for example a heating elementmade of metal or ceramic material, inside a plastic injection-mouldedpart is to inject it directly as an insert in the injection-moulding ofthe plastic injection-moulded part. The problem with this method ofproduction is that the pressure arising inside the injection mould isproblematic for breakable materials, for example ceramics, sincebreakable materials like ceramic or glass cannot be randomly pressed.

BRIEF SUMMARY OF THE INVENTION

It is against the above background that the present invention providescertain unobvious advantages and advancements over the prior art. Inparticular, the inventor has recognized a need for improvements inmethods for producing plastic injection-moulded parts.

In accordance with one embodiment of the present invention, a method forproducing a plastic injection-moulded part having an insert made of amaterial different from the plastic material is provided, the methodcomprising the steps of: (a) introducing and positioning the insert in acavity of an injection mould; (b) setting the clamping force of theinjection mould, on a clamping mechanism, to a maximum forcepredetermined by the material of the insert; and (c) seamlesslyencapsulating the insert with the plastic material of the plasticinjection-moulded part inside the injection mould, wherein theencapsulating is partial or complete.

In accordance with another embodiment of the present invention, a rapiddiagnosis appliance for evaluation of a test strip, having a housingbody, at least part of the housing body being produced in accordancewith the method of the invention is provided, wherein an insert actingas a heating element is seamlessly embedded in a system-critical areainside the housing body made of plastic material.

Although the present invention is not limited to specific advantages orfunctionality, it is noted that, within one operation in theinjection-moulding process in multi-component injection moulding, it isnow possible to work the plastic material or materials and at the sametime also breakable materials such as ceramic or glass, because theinjection mould in which the plastic injection-moulded part isencapsulated with an insert made of breakable material such as ceramicor glass, is equipped with a spring-actuated clamping mechanism.

It is thus possible, on the injection mould, to set the maximum pressingforce to the maximum force that can be applied to the breakablecomponent. This in turn opens up the possibility of also embedding, asinserts in plastic components, different breakable materials which cantake up different forces. The maximum clamping force can thus in eachcase be adapted individually to the material used as insert.

The breakable component can optionally be coated with a damping layer.The damping layer used can, for example, be a lacquer which is appliedacross the entire surface either to the breakable components or to thesteel parts of the injection mould which may come into contact with theinsert of breakable material such as ceramic or glass, which contactwould otherwise lead to fracturing of the breakable material. It ispossible for the damping layer, in the form of a lacquer layer, to beapplied in such a way that the insert to be embedded in the plasticmaterial is completely surrounded by this damping layer. On the otherhand, it is possible for the damping layer to be applied as a framearound the breakable component to be embedded as an insert in theplastic material, so that the contact between the steel parts of theinjection mould and the insert of breakable material is damped only atcertain places.

If for example, analysis chips, in particular biochips, are produced asinserts in plastic material, in the manner of the injection-mouldingmethod of the present invention, they can be encapsulated by a plasticframe, so that, in the production of biochips, a damping layer is to beapplied only partially and other areas of the glass, which alsorepresents a breakable material, can remain untreated. The untreatedportions of the glass can be covered at a later stage with suitablereagents required for using the insert with a glass support as basematerial.

The production method of the present invention for production of aninsert of breakable material, such as ceramic or glass, integrated in aplastic component is characterized by a high degree of processreliability. Since the production process in question ismould-dependent, i.e. coupled to the injection mould, assembly costs arecompletely dispensed with, as is the associated risk of incorrectassembly. With the production method of the present invention forembedding an insert made of breakable material in a plasticinjection-moulded part to be injection-moulded, seamless embedding of aheating element made of metal or ceramic material into a plastic shellof the plastic housing of a rapid diagnosis appliance is readilypossible. By virtue of the seamless embedding of a heating element ofceramic or metal material into a plastic injection-moulded part to beproduced in one and the same operation, the insert is embedded in aliquid-tight and form-fitting manner in the plastic material.

These and other features and advantages of the present invention will bemore fully understood for the following detailed description of theinvention taken together with the accompanying claims. It is noted thatthe scope of the claims is defined by the recitations therein and not bythe specific discussion of features and advantages set forth in thepresent description.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description of the embodiments of the presentinvention can be best understood when read in conjunction with thefollowing drawings, where like structure is indicated with likereference numerals and in which:

FIG. 1 shows a perspective view of a rapid diagnosis and measurementappliance,

FIG. 2 shows an exposed housing opening of a rapid diagnosis appliance,

FIG. 3 shows a detail of the housing body of a rapid diagnosis andmeasurement appliance according to the view in FIG. 1, with anintegrated heating element made of a breakable material, for exampleceramic,

FIG. 4 shows a diagrammatic representation of an injection mould withvariable clamping force,

FIG. 5 shows a glass body surrounded by a frame made of plasticmaterial,

FIG. 6 shows a ceramic body which is provided on its top face with alacquer coating serving as a damping layer, and

FIG. 7 shows an insert made of ceramic material, embedded seamlesslyinto a plastic material.

Skilled artisans appreciate that elements in the figures are illustratedfor simplicity and clarity and have not been necessarily drawn to scale.For example, the dimensions of some of the elements in the figures maybe exaggerated relative to other elements to help improve understandingof the embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The perspective view in FIG. 1 is of a rapid diagnosis appliance whosehousing body is a plastic injection-moulded part.

A rapid diagnosis appliance 1 shown in FIG. 1 comprises a housing body 2made of a plastic material. Provided on a front face 6 of the housingbody 2 there is a cover element 3 whose lower margin lies above aninsertion opening 4. The insertion opening 4 comprises an insertiontongue 5 acting as a bearing surface for a test strip to be insertedinto the inside of the housing body 2. The rear face of the housing body2 of the rapid diagnosis appliance 1 is indicated by reference number 7.The rapid diagnosis appliance 1 is used for evaluation of test stripswhich are to be inserted into the housing body 2 and are wetted withblood of human or animal origin. The test strips have chemicalsubstances which react with the applied quantity of blood, for exampleto permit blood sugar measurement. In order to perform the measurementon the test strip, the housing body 2 contains heating elements,electrical contact elements for the test strip to be inserted into theinsertion opening 4, and also evaluation electronics, and an opticaldisplay.

The view in FIG. 2 shows the front face 6 of the housing body 2 of therapid diagnosis appliance 1. Formed in the front face 6 of the housingbody 2 there is a housing opening 10 which can have an oval and roundedappearance, as shown in FIG. 2. The underside of the housing opening 10is limited by the insertion tongue 5. On both sides of the insertiontongue 5 there are raised insertion rails 11 between which a test strip(not shown in FIG. 2) to be introduced into the insertion opening 4 canbe pushed into the inside 13 of the housing body 2. The test strip to beintroduced into the insertion opening 4 is guided on the one hand by thetwo insertion rails 11 and on the other hand by the top face 14 of theinsertion tongue 5.

FIG. 3 shows a system-critical area in the inside of the housing body ofa rapid diagnosis appliance, for example.

Within a system-critical area defined by reference number 15 inside thehousing body 2, an insert 16 is integrated into a plastic componentwhich has, for example, been injection-moulded as the lower shell of thehousing. In the case of a rapid diagnosis appliance 1, the insert 16embedded in the plastic material is a heating element which can be madeof a breakable material such as ceramic or of metal. When a test stripis pushed in, the insert 16 designed as a heating element generates,inside the housing body 2, a temperature at which the reagent area onthe inserted test strip is brought to a temperature permitting ameaningful measurement in a rapid diagnosis appliance.

In the view in FIG. 3, the insert 16 is integrated with seamlessembedding 17 in the lower shell of the housing body 2. The test strip(not shown in FIG. 3) covers the top face of the insert 16 designed as aheating element, and contact can be made with it via electrical contacts19. A long side 20 of the insert 16 extends parallel to the measurementedge of a measurement strip, while the shorter transverse side 21 of theinsert 16 extends perpendicular to the direction of insertion into theinside of the housing body 2.

The test strip, which covers the insert 16 when inserted into thehousing body 2, is heated by the ceramic insert 16 designed as a heatingelement and is brought to a temperature required for a meaningfulmeasurement result. This depends on the reagents provided in the teststrip.

FIG. 4 is a diagrammatic representation of an injection mould in whosecavity a plastic material and a breakable material can beinjection-moulded at the same time.

The view in FIG. 4 shows an injection mould 30 comprising a first mouldhalf 31 and a second mould half 32. The first mould half 31 can bedisplaced relative to the second mould half 32 in the direction of thedouble arrow, i.e. can be opened and closed. The first mould half 31 andthe second mould half 32 delimit a cavity 33. With the first mould half31 and the second mould half 32 in the closed state, they are closed viaa clamping mechanism. The contact pressure, which can be set via theadjustable contact pressure mechanism 34, is dependent on the forcewhich can be withstood by the breakable material from which the insert16 is made.

The first mould half 31 and the second mould half 32 are connected toone another via a hinge. In the first mould half 31, or in the secondmould half 32, it is possible to provide sprue channels 36 through whichthe plastic material flows into the cavity 33 formed by the mould halves31 and 32. The insert 16 is taken up and positioned by a press stamp 34a. When the mould halves 31, 32 are closed together, the insert 16 ispressed flat against the first mould half 31 and thus held in position.The recess for embedding of the insert 16 is produced by introducing theinsert 16 into the cavity 33 and then encapsulating it.

The view in FIG. 5 shows an insert 16 made of glass 40. The insert 16made as a glass body 40 is surrounded on its peripheral surface by aplastic frame 42. On its long sides, the plastic frame 42 hasprojections 43, so that a not inconsiderable part of the top face andbottom face of the glass body 40 remains as an exposed surface 41.Arranging a plastic frame 42 around the glass body 40 is expedientparticularly in the production of biochips whose top faces can becovered or coated at a later stage with suitable reagents needed for theuse of biochips. By means of the plastic frame 42 surrounding the glassbody 40, it is possible to avoid contact between the steel parts of themould halves 31, 32 and the breakable glass body 40, since the steelparts of the first and second mould halves 31, 32 make contact only withthe outside of the plastic frame 42 surrounding the glass body 40.

FIG. 6 shows an insert 16 in the form of a ceramic body 50 on whose topface 51 a damping layer 53 in the form of a lacquer layer is appliedacross the entire surface. In the view in FIG. 6, the bottom face 52 ofthe ceramic body 50 is untreated. In addition to a full-surface coatingwith a lacquer layer 53 as damping layer shown in FIG. 6, it is alsopossible to coat only some areas of the ceramic body 50, both on its topface 51 and on its bottom face 52, with a damping layer in the form of alacquer layer.

The view in FIG. 7 shows that an insert, which for example can be madeof a ceramic material or of a metal material, is embedded seamlessly ina plastic material 60. The insert 16, 50 shown in FIG. 7 can be embeddedseamlessly as a heating element in a housing body 2 of a rapid diagnosisappliance (compare the detail in FIG. 3) and can be provided within thesystem-critical area 15. System-critical area 15 is to be understood asthe area within a rapid diagnosis appliance 1 where excess blood from atest strip inserted into the inside of the rapid diagnosis appliance 1may be present, or where aggressive cleaning agents, used to clean theinside of the housing of the rapid diagnosis appliance 1 from time totime, may be present.

By virtue of the insert 16 being designed according to the invention asan integral component of a housing body 2 made of plastic material 60,the seams between the inserts 16, 50 and the plastic material 60, whicharise when the insert 16, 50 is bonded or mechanically locked in place,are avoided by the solution of the invention. By virtue of the solutionof the invention, the particular advantage achieved is that the top faceof the insert 16, 50 forms a uniform plane with the top face of theplastic material 60, thus making it easier to insert a test strip at theinsertion opening 4 into the inside of the housing body 2 of a rapiddiagnosis appliance 1.

In the production method of the invention for production of a plasticcomponent, with an insert made of breakable material embedded in thesame operation, a simple mould-dependent production process can beprovided which is characterized in particular by a high degree ofprocess reliability. Incorrect assembly, which occurs in the assemblyprocesses known in the prior art, can be ruled out. Within thesystem-critical area 15, which may be contaminated by aggressivecleaning media and by deposits of blood plasma, seamless embedding of aninsert made of ceramic material, i.e. breakable material, into theinsertion area of a test strip is possible, characterized by seamlessembedding in the plastic material 60. By virtue of the fact that themethod of the invention ensures that there are no seams permittingseepage of liquid, electronic components lying underneath the ceramicinsert 16, 50 are effectively protected from these media. Fitting aheating element at a later stage into a rapid diagnosis appliance, atconsiderable cost, as is the case in the prior art, is now no longernecessary. The seamless embedding 17 of the insert 16, 50 of breakablematerial, for example metal or ceramic, also advantageously permits aliquid-tight and form-fit connection between the plastic material 60 ofthe housing body 2 and the insert 16, 50 made of breakable materialwhich, along its long side 20 and along its transverse side 21 (cf. viewaccording to FIG. 3), is embedded seamlessly in the plastic material 60between two guide rails for guiding the test strip to be inserted intothe inside of the housing.

It is noted that terms like “preferably”, “commonly”, and “typically”are not utilized herein to limit the scope of the claimed invention orto imply that certain features are critical, essential, or evenimportant to the structure or function of the claimed invention. Rather,these terms are merely intended to highlight alternative or additionalfeatures that may or may not be utilized in a particular embodiment ofthe present invention.

For the purposes of describing and defining the present invention it isnoted that the term “substantially” is utilized herein to represent theinherent degree of uncertainty that may be attributed to anyquantitative comparison, value, measurement, or other representation.The term “substantially” is also utilized herein to represent the degreeby which a quantitative representation may vary from a stated referencewithout resulting in a change in the basic function of the subjectmatter at issue.

Having described the invention in detail and by reference to variousspecific embodiments thereof, it will be apparent that variations andmodifications may be made without departing from the scope of theinvention defined in the appended claims. More specifically, althoughsome aspects of the present invention are identified herein as preferredor particularly advantageous, it is contemplated that the presentinvention is not necessarily limited to these preferred aspects of theinvention.

What is claimed is:
 1. A rapid diagnosis appliance for evaluation of atest strip, the appliance comprising: a plastic housing body having aninternal system-critical area; and an insert seamlessly embedded in aliquid-tight manner in the system-critical area, wherein the insert ismade of a breakable material, and has a damping layer covering anexposed surface of the insert towards an injection mould, wherein thedamping layer is a lacquer layer that protects the insert from breakingwhen a maximum clamping pressure is applied during injection moulding,and wherein the maximum clamping pressure is predetermined by thematerial of the insert.
 2. The rapid diagnosis appliance of claim 1,wherein the insert functions as a heating element.
 3. The rapiddiagnosis appliance of claim 2, wherein the insert is an integralcomponent of at least part of the housing body.
 4. The rapid diagnosisappliance of claim 2, wherein the insert is made of ceramic or metalmaterial.
 5. The rapid diagnosis appliance of claim 1, wherein theinsert is made of glass.
 6. The rapid diagnosis appliance of claim 2,wherein the insert is received with a form fit in part of the housingbody.